Apparatus for supplying heat for hot gas defrosting systems



APPARATUS FOR suPPLmc HEAT FOR no'r GAS DEFROSTING SYSTEMS Filed Dec. 10. 1953 Sept. 24, 1957 R. M. HENDERSON 2 Shgets-Sheet 1 INVENTOR.

RAY M. HENDERSON BY WWW ATTORNEY I :m MW

Sept. 24; 1957 R, MQHENDERSON APPARATUS FOR SUPPLYING HEAT FOR HOT GAS Dsfikos'rmc SYSTEMS Filed Dec. 10, 1955 2 Sheets-Sheet 2 INVENTOR." RAY M. HENDERSON AT TOR/V5) United States Patent APPARATUS FOR SUPPLYING HEAT FOR HOT GAS DEFROSTING SYSTEMS Ray M. Henderson, Bellaire, Tex. Application December 10, 1953, Serial No. 397,369 11 Ciairns. (Cl. 62-3) This invention relates to refrigeration apparatus and more particularly to improved means and methods for supplying heat for hot gas defrosting.

Some of the means and methods embodied in the present invention are disclosed in part in my pending application for patent, Serial No. 280,263 filed April 3, 1952, for Defrosting System for Refrigeration Evaporators, now Patent No. 2,748,581, granted June 5, 1956, which discloses a means and method of evaporation of liquid refrigerant in a secondary evaporator to provide hot gas for defrosting, by bringing the liquid refrigerant from the receiver into heat exchanging relation with a heat bearing substance and controlling the amount of heat exchanged thereby by regulation of the amount of heat bearing substance supplied thereto.

In the development of the means and methods disclosed in the above noted application it was discovered that liquid refrigerant which was condensed in the refrigerator evaporator and returned directly to the receiver of the system, especially in systems in which the evaporator temperatures were comparatively low, entered the receiver at a very low temperature, and because of the fact that liquids generally used for refrigeration generate very little or no pressure when held at low temperatures and further because the presence of pressure in the receiver is required to expel the liquid therefrom, it was definitely determined that heating of the liquid so returned to generate pressure for its expulsion from the receiver was not only desirable but necessary to the correct performance of the system during the defrosting operation. This was found to be especially true in systems wherein the flow of liquid from the receiver to the secondary evaporator was restricted by an expansion valve or similar device. It became obvious that the suction pressure of the secondary evaporator could not be greater than the pressure on the liquid in the receiver which propels the liquid into said evaporator, and further that a restriction to the flow of the liquid would necessitate a rather wide difference of pressure to cause adequate flow of the liquid to the secondary evaporator.

It became obvious that a gas pressure must be maintained in the receiver which should be commensurate with the desired suction pressure during the reverse cycle or the defrosting operation. T o accomplishthis pressure in the receiver, the liquid in the receiver must be held at a temperature at which a sufiicient amount of gas pressure will be generated to expel enough refrigerant therefrom to create the desired suction pressure for defrosting.

With these developments and observations in mind, it is an object of this invention to provide in combination with reverse cycle defrosting, means for causing the liquid refrigerant which is condensed as a result of the defrosting and being returned from the evaporator to the receiver to be heated, either during its return or after it has been so returned, and thus generate enough pressure in the receiver to expel sufficient refrigerant therefrom (either in liquid and/or gaseousstate) to generate a 2,807,145 Patented Sept. 24, 1957 sufficient amount of vaporized refrigerant as to create a suction pressure commensurate with the capacity of the compressor to thereby obtain the desired results during the defrosting operation.

Another object is to provide a water supply as the heating means for transmitting heat to the refrigerant and to regulate this water supply and thereby regulate the amount of heat transmitted and, as a result, control the suction pressure of the system throughout the defrosting operation.

Another object is to provide in a refrigeration system, a heat exchanger wherein refrigerant in the system is brought into heat exchanging relation with water and to associate with the system a regulating valve to regulate the amount of water supplied during the refrigeration cycle of the system, and a second regulating valve to regulate the amount of water to be supplied during the defrosting cycle.

Another object is to provide in combination with a refrigeration system, means for reversing the flow of refrigerant to thereby cause the refrigerant to be condensed in the evaporator and transmitted therefrom in a reverse direction through the receiver and condenser to the compressor, together with means intermediate the evaporator and condenser for heating said liquid refrigerant before passing through the condenser in its reverse direction of flow to the compressor.

Another object is to provide in a hot gas defrosting system, a secondary evaporator for generating hot gas for defrosting, by means for causing reverse flow of refrigerant through the condenser in heat exchanging relation with a source of water supplied thereto, and a water regulating valve operable in response to changes of the temperature of the water supplied to thereby regulate the amount of water supplied throughout the defrosting operation.

Another object is to provide in a reverse cycle defrosting system wherein the liquid refrigerant which is condensed in the evaporator as a result of the defrosting is returned through means by-passing the expansion valve to-the receiver and then expelled by pressure into the condenser for evaporation, means intermediate the evaporator and the condenser for heating said liquid and thereby generate gas pressure in the receiver to expel the liquid therefrom through a provided liquid outlet, together with associated means to release a portion of the pressure so generated and additionally means operable in response to a condition of the refrigerant in the condenser to regulate the amount of pressure released during the defrosting operation.

Another object is to provide a new method of supplying and controlling heat for hot gas defrosting systems associated with refrigeration systems.

Another object of the invention is to provide in place of the usual receiver of a refrigeration system or where the system has a so-called combination receiver-condenser, a new combination receiver-condenser for water cooled condensing units which will function as an auxiliary condenser during the refrigeration cycle or as an evaporator during the defrosting cycle, and which is so constructed that the portion for containing water is situated outside the refrigerant container to thereby eliminate the possibility of flooding water into the refrigeration system in case of freezing and bursting the water containing means.

Another object is to provide a new combination receiver-condenser for condensing units comprising separate associated refrigerant and water container means for conducting refrigerant and water therethrough in heat exchange relation, in which the exterior of the refrigerant retaining means provides one portion of the Water containing means and the exterior of the said receiver-condenser provides the other portion of the said means, and in which the bursting strength of the walls of the refriga erant container means is greater than that of the exterior walls of the said receiver-condenser.

Other objects will become apparent from the following description taken in connection with the accompanying drawings in which:

Figure 1 is a schematic view of a complete air cooled refrigeration system comprising an evaporator, an expansion valve, a compressor, a condenser, a receiver of my new combination receiver-condenser type, and the connecting conduits essential to such a system having associated therewith a reverse cycle defrosting system embodying my invention and in which are two water regulating valves with the valve employed during defrosting being controlled by refrigerant temperature;

7 Figures 2 and 3 are sectional views showing details of the two water regulating valves in the system disclosed in Figure 1;

Figure 4 is a schematic view of a water cooled refrigeration system having associated therewith a reverse cycle defrosting system embodying my invention which also employs the water regulating valves shown in Figures 2 and 3, with the regulating valve operable during defrosting being controlled by refrigerant pressure;

Figure 5 is a view of still another system showing associated therewith a reverse cycle defrosting system embodying my invention and wherein the water regulating valves are employed, but having the valve which is regulated during defrosting controlled by refrigerant temperature instead of pressure.

Preliminary to a detailed description of the novel means and methods disclosed herein, reverse cycle heating by refrigeration systems and/ or reverse operation for defrosting should be well understood. Reverse cycle operation of a conventional refrigeration system is accomplished by reversing the direction of flow of refrigerant through the major functioning parts of the system, which in turn causes reverse action of function of at least some of these parts. Thus, the hot gas from the high side of the compressor is diverted to flow to the evaporator to thereby cause the evaporator to become a condenser and the liquid condensed thereby is returned by a by-passing of the expansion valve, to the receiver, from where it is passed in reverse direction through means provided into the condenser through which the flow of refrigerant has been reversed by a connection to the suction side of the compressor. In established practice of reverse cycle operation of refrigeration systems, a liquid connection is usually provided between the receiver and the condenser to conduct liquid from the receiver to the condenser to thereby convert the condenser into a secondary evaporator for the purpose of evaporating the refrigerant therein to absorb heat for heating or defrosting the evaporator. In this liquid connection, a flow restricting means, such as an expansion valve, capillary tube, float valve or syphoning device, is normally used to restrict or control the flow of liquid to the condenser. The reverse cycleoperation is ordinarily initiated and terminated by so-called reversing valves, usually of the well known four way type which are operable, to disconnect the condenser from the discharge side of the compressor and connect it to the suction side, and to disconnect the evaporator from the suction side of the compressor and connect it to the discharge side. Thus, the refrigerant is evaporated in the condenser and condensed in the evaporator.

In reverse cycle operation for ordinary applications such as dwelling cooling and heating or for defrosting comparatively high temperature refrigeration systems in which the time involved for change over from one cycle to the other is not criticaLthe presently used type of reverse cycle operation and change over therefor has been found to be satisfactory. However, in freezer applications where temperatures are held extremely low, the dependence upon ordinary reversing valves alone to accomplish the change over from the refrigeration cycle to the defrosting cycle is not practical because of the extended period of time required to accomplish this change over from one cycle to the other.

In the development of the defrosting systems I have determined that the extremely low temperature of the liquid refrigerant that is returned to the receiver during the defrosting operation, and especially at the very beginning of this operation, is responsible for considerable delay in accomplishing complete change over in the reverse cycle operation. This extremely cold liquid, as previously explained herein, causes, in refrigeration systems which are operated at temperatures below zero, a complete elimination of receiver pressure, which is essential for the expulsion of refrigerant from the receiver for further defrosting operation. Of course the receiver shell, and other components with which the refrigerant comes in contact, will eventually accumulate sufiicient heat to gradually build up enough pressure in the receiver to expel refrigerant therefrom and put the system into complete reverse cycle operation, but as previously stated, the time required to accomplish this is such that the defrosting cycle is extended an undesirable period of time, causing the product load in the refrigerator to be adversely effected by a rise in temperature. With my present invention I overcome this undesirable feature in reverse cycle defrosting by heating the returning liquid so as to provide a gas pressure which will cause the movement of refrigerant through means provided in the reverse cycle defrosting system to be accelerated.

Referring to Figure 1 in detail, there is disclosed a well known refrigeration system with which I have associated the hot gas defrosting system embodying my invention.. It will be seen that the refrigeration system comprises an evaporator E of the coil type which will be positioned in a space or chamber to be refrigerated. The conventional system also includes the compressor C, condenser D and the liquid receiver R. The condenser D is of the air cooled type and is of known construction. As seen in the drawings, the receiver is connected to one end of the evaporator by a liquid line L with which is associated the usual expansion valve X. There is also a suction line S connected at one end to the low side 11 of the compressor and at the other end to the evaporator. To this suction line is clamped the bulb B which controls the expansion valve X in a well known manner. The high side 12 of the compressor is connected by a conduit 13 to one. end of the condenser D, the other end of the condenser being connected into the receiver R by the conduit 14.

With this conventional refrigeration system, the refrigerant in the evaporator absorbs heat from the space it is cooling because the refrigerant is held under a pressure at which the liquids boiling temperature is below the temperature of the surrounding air or material in the chamber. The heat flow into the refrigerant causes it to boil and therefore is converted into a vapor. This vapor will then pass through the suction line S to the compressor C where it will be compressed to a pressure at which the temperature of the refrigerant is somewhat higher than the cooling medium which will be the air employed in cooling the condenser D. At the condenser the heat is transferred from the compressed vapor to the cooling medium of the condenser, thereby causing the refrigerant to condense and liquefy. The liquid refrigerant then passes into the receiver R and subsequently through the liquid line L to the evaporator E through the expansion valve. This expansion valve is designed to keep the line as full of refrigerant as possible and prevent any return. In the evaporator the pressure of the refrigerant becomes reduced, where it again boils and therefore extracts more heat from the chamber being cooled, with the result that it is again changed to a vapor and passes back to the compressor.

Associated with the conventional refrigeration system shown is a defrosting system which is of thehot gas type.

Defrosting is accomplished by the employment of a reverse valve RV and it is connected into the suction line S between the evaporator and the compressor and also in the conduit 13 between the compressor and the condenser. When the refrigeration cycle is operating, the reverse valve is conditioned so that vapor passes through the suction line to the compressor and then from the compressor to the condenser as already described. However, when defrosting is desired to be initiated, the reverse valve is operated, preferably automatically, so that the high side 12 of the compressor will be connected into the suction line and the compressed vapor from the compressor will go directly to the evaporator instead of to the condenser. Further, the line 13 leading to the condenser will be connected to the low side of the compressor so that liquid can be brought through the condenser from the receiver to the compressor in vapor form. In this operation of defrosting, the heat exchanger comprising the receiver will function as the primary means for the evaporation of liquid for defrosting and the condenser will act more as a superheater than an evaporator. This condenser being of the air cooled type, it will function as a heat exchanger to absorb heat from the surrounding air, and as a result the vaporized refrigerant coming from the receiver will be further expanded or superheated as it passes through the condenser to the compressor as it is pumped by the compressor to the evaporator being defrosted. When the vapor reaches the evaporator it will give up its heat to defrost the evaporator coils and as a consequence the vapor will be changed back to a liquid and flow back through the line L to the receiver R. In order that the returning liquid from the evaporator can by-pass the expansion valve which will be closed, there is provided in the system shown in Figure l a by-pass line 15 and a check valve 16, the check valve permitting fluid to flow only from the evaporator to the line L and not in the reverse direction so that during the refrigeration cycle the expansion valve can still function in its proper manner.

The use of conventional liquid receivers and/or combinations thereof as evaporators for absorbing heat for defrosting have been found inefficient and/ or impracticable. The conventional receiver which is used only for storage of liquid refrigerant is a very inefficient heat exchanger because the transfer of heat from the surrounding air to the limited usable surface of an average liquid receiver would obviously be inadequate to absorb enough heat for defrosting, even for relatively high temperature refrigerators. It is obvious that the usable surface would be limited by the amount of boiling liquid contained in the receiver. Therefore, reverse operation of a conventional air cooled condensing unit, wherein the receiver without modification is used as an evaporator, has been found to be impracticable.

In the case of known combination receiver-condensers which are used to replace the straight conventional receiver tank, such as shell and tube or shell and coil condensers, in which the refrigerant condensed therein is accumulated and stored in the bottom, the same problem of inadequate heat exchange surface is encountered. In these so-called receiver-condenser combinations it is common practice, because of the added efficiency of the condensing operation derived therefrom, to position the water conduits in the interior of the receiver where they will be surrounded by the hot refrigerant gas which is to be condensed, and although some of the heat exchange surface provided by these conduits becomes submerged in the liquid at times, most of the surface is above the liquid level. Therefore, in reverse cycle operation wherein these receiver-condensers are converted into evaporators, most of the heat exchange surface of these conduits is not effective because it is above the level of the boiling liquid. Further, the portion of the heat exchange surface that is submerged, being inadequate, causes the system to operate on a very low suction pressure and usually results in freezing and bursting of the water conduits. This, of course, fills the refrigeration system with water which results in costly repair bills.

In the system shown in Figure 1 as embodying my invention, the conventional type of liquid receiver is used, and although, as previously stated, the amount of usable heat exchange surface is limited, it has been found to be adequate to absorb heat for easy defrosting jobs if the available surface is efficiently utilized, and to utilize all of the available surface, a tank T is provided which completely surrounds the receiver R, and when filled with water the receiver will be completely surrounded by water.

In addition to the advantages of efficient utilization of all available heat exchange surface, this exterior water containing shell has a definite advantage over the placement of water conduits in the interior of the receiver or the so-called receiver-condenser, either of the shell-tube type or shell-coil type.

In refrigeration heat exchanger of these above mentioned known types where water is brought into heat exchanging relation with a boiling refrigerant, freezing of the water and bursting of the water container is always a possibility. Therefore, by positioning the water container on the outside of the receiver as I propose, the possibility of flooding water into the refrigeration system in case of a bursted water conduit is eliminated, because the bursting strength requirements of refrigerant containers is greater than that of water containers and therefore, in case of freezing, the outside wall of the water container or tank T would burst, rather than the wall which separates the refrigerant from the water. Further, by having this tank on the outside of the receiver where space is not limited, the space containing the water between the shell of the receiver and the shell of the tank can be made large enough to minimize the possibility of freezing enough to burst the tank. This tank will be filled with water and water will be continuously flowing through the tank so that as the water gives up its heat to the liquid in the receiver, causing evaporation thereof, new heat will be continuously supplied by incoming water. As shown, one end of the tank is connected to a water inlet line WL and the other end of the tank is connected to a water discharge line WD.

The control of the water through the water line WL to the tank is a very important feature of my invention as this control must be accomplished in a manner so that an efficient system will result, both during the refrigeration cycle and the defrosting cycle. Each cycle will require an entirely different control of the water supply to the tank, depending upon the functional requirements involved. To accomplish proper control of the water supply, I divide the water line into two sections 17 and 18 and in each of these sections I provide a control valve with the valve in section 17 indicated generally as control valve VD and in section 18 the control valve VR, the valve VD being employed for controlling the supply of water during defrosting cycle and the valve VR being employed to control the water during the refrigeration cycle.

Under normal conditions it probably would not be necessary to control the water supply during the refrigeration cycle as the condenser generally has sufiicient capacity to accomplish most of the requirements in connection with the cooling of the refrigerant. However, when abnormal conditions occur, such as extremely warm ambient temperatures, or an excessive product load on account of the food being cooled, the head pressure of the compressor will be raised above normal. As head pressure increases, the condenser is incapable, because of size, of accomplishing the desired rapid heat exchange and thus the vapor will not be changed to a liquid as rapidly as desired. I employ this increased head pressure in the compressor when abnormal conditions are created to control the valve VR which is a pressure control valve and disclosed in detail 'in Figure 2. It will be noted that'the valve VR is connected to the high side of the compressor by a small tube 19.

The valve VR has a body with a passage 21 therethrough which is connected into the supply water line and associated with this passage is a partition 22 having an opening therein with which is formed a valve seat 23. A valve 24 cooperates with this seat and is normally biased onto the seat by a spring 25, the pressure of which can be controlled by a screw 26. This spring will normally close the valve, but it can be opened by fluid pressure on a bellows 27 which is connected by a stem 28 with the valve element. The bellows is within a chamber 29 on the side of the valve opposite the spring and connected to this chamber is the tube 1 for controlling the pressure therein. The screw 26 will be adjusted so the valve will be held closed by the spring during normal operation of the refrigeration system. When the compressor head pressure builds up, this pressure will be transmitted to the chamber 29 through the tube 19 and will cause the bellows to so function that the valve will be opened. Preferably, a considerably high head pressure is desirable before the valve VR opens so that a comparatively high pressure and temperature will be maintained on the refrigerant in the receiver and on the water in the tank T. By having the water in the tank T at a high temperature, it can then be employed eificiently for evaporation of refrigerant during the initial phase of the defrosting cycle, as will later become apparent.

The valve VD, which will control the flow of water to the tank during the defrosting, is also a pressure controlled valve but it is constructed to be controlled by a thermal bulb TB which is positioned in the tank and preferably near the water discharge outlet WD thereof. The construction of the valve VD is somewhat similar to the valve VR, but the parts are so reversed that a spring will tend to bias the valve toward open position. As shown in Figure 3, the valve VD has a body 30 positioned in the section 17 of the water inlet line and this body has a partition 31 with a hole 32 therein with which is associated a valve seat 33. Cooperating with this valve seat is a valve element 34 acted upon to move to an open position by a spring 35, the tension of which can be adjusted by a screw 36. On the body opposite the spring is a bellows 37 positioned in a chamber 38 and this chamber is connected by a tube 39 to the thermal bulb TB. 7 When the gas pressure in the thermal bulb decreases, due to a decrease in temperature at the bulb, that is, the water of the tank, the valve will be opened by the spring and consequently flow of water can then take place through the tank by way of the valve VD and the water line section 17. The cooler the water becomes in the tank, the less pressure acting on the bellows, and consequently the greater will become the opening of the valve VR. Thus, with greater flow of water through the tank, there will be more heat supplied to the tank for transfer to the refrigerant for vaporizing purposes during the defrosting cycle.

When the system is operating on its refrigeration cycle, the valve VR will be closed, if conditions are normal. The valve VD will also be closed as the temperature of the water is such that the gas pressure in the thermal bulb will maintain this valve closed. If now there should be an overload on the refrigeration system, causing abnormal conditions with the result that a pressure head will be built up at the compressor, the valve VR will be opened and water in the tank T surrounding the reservoir will cause the receiver to act as a secondary condenser, thus increasing the condenser capacity of the system. The result will be that water will flow through the tank and aid in condensing the refrigerant. The valve VR, however, will not open up until a relatively high head pressure is built up on the compressor and thus the water in the tank T willacquire a fairly high heat content before there is any flow of. water through the tank.

When the defrosting cycle begins, the reversing valve RVfwill be operated and at this time the water in the tank T will begin to act as a secondary heat exchanger to transfer heat into the cold refrigerant coming from the evaporator by Way of the line L. This will cause the refrigerant to absorb heat and become vaporized, with the result that this vaporized refrigerant can then be pumped through the compressor and back into the evaporator to accomplish the defrosting thereof. As heat is continued to be transferred from the water to the refrigerant in the the receiver (which heat of the water will be fairly high because such, as already mentioned, is maintained high by the valve VR not opening during the refrigeration cycle except under high head pressures at the compressor), there will be continued vaporizing of the refrigerant in the receiver and this refrigerant can then be recompressed by the compressor and forced into the evaporator to accomplish rapid defrosting. The liquid coming from the evaporator, after transferring its heat to the evaporator to accomplish defrosting, will always be rapidly vaporized because of plenty of heat which is available from the water continuously passing through the tank. If the water in the tank should begin to cool so that rapid vaporization is not taking place, then the thermal bulb will have its gas pressure decreased, with the result that the spring can open the valve VD to a greater extent and cause water to flow from the water line through the tank and out the water discharge. pipe and thus supply additional heat to take care of all requirements.

It will thus be seen that the heat exchanger means for the evaporation of the refrigerant to provide sufiicient heatladen gas for defrosting is fully controlled as to initiation, regulation and termination. The control of the heat exchanger will be in response to all functional requirements during the defrosting cycle and the defrosting cycle will take place rapidly and with efiiciency. The pressure in the receiver will always be maintained high by the absorption of heat from the heat exchanger means so there will always be expelled sufficient refrigerant to supply the necessary vaporized refrigerant to accomplish the rapid defrosting. Furthermore, the defrosting will be efficient from the beginning of the defrosting cycle, because this is assured by the fact that the heat in the body of water in the tank will be high when the defrosting cycle commences because the valve VR and its method of control during the refrigeration cycle will always assure a high temperature in the tank of water.

Therefn'geration system and defrosting system shown in Figure l is well adapted for the air cooled type of refr'igeration system as these systems are used most on light duty. applications wherein extremely low temperatures are notrequired and the product load is not too heavy. Generally, it is desired in these systems to keep the cost of equipment low and the operation efiicient and this is readily accomplished by the system shown in Figure 1 as all that is required to bring about an efficient refrigeration operation, which can also take care of overloads and accomplish quick defrosting, is to provide the two additional water control valves, the heat exchange means in the form of the tank T surrounding the receiver R and suitable control means for the valves so that these valves will be responsive to all functional requirements of the refrigeration system and the defrosting system.

An advantage of this receiver-evaporator combination (the receiver R and tank T) is the simplicity of the evaporating system provided for defrosting. There is no attempt made to transmit raw liquid from the receiver to the condenser during the defrosting cycle as the condenser is used only as a superheater for the previously vaporized refrigerant. Therefore, the maintenance of a pressure difference between the receiver and the condenser for transmitting liquid from the receiver to the condenser is not necessary. Further, the use of special connections between the receiver and condenser and regulating valve means to control the supply of liquid for evaporation is eliminated, because even an over-charge of refrigerant in excess of the receiver capacity would only cause a small amount of liquid to be expelled from the receiver into the condenser where it would be evaporated by the heat of the air passing therethrough and could reach the compressor only after it is vaporized.

Another advantage of this new receiver-condenser is that it is adaptable to any cooled condensening unit with practically no alteration to the unit except the replacement of the receiver with this combination receiver and condenser.

In Figure 4 I have illustrated my invention as being embodied in structure especially adapted for use with a refrigeration system of the water cooled type, and par ticularly one in which there is provided a pressure regulating valve for the receiver which functions to relieve receiver pressure when the defrosting cycle is initiated. The conventional parts of the refrigeration system are designated by the same letter as in the system shown in Figure 1. It will be noted there is an evaporator E, a a compressor C, a receiver R and an expansion valve X controlled by a bulb B. The condenser employed is of the Water cooled type and is indicated by the letters DW. There is also provided the by-pass '15 for the expansion valve, together with the check valve 16 which will function during the defrosting cycle Whenever the reversing valve RV is properly conditioned, :all as previously described. Surrounding the receiver is the water tank T which has water supplied thereto from the water line'WL and this water is discharged from the tank through the water discharge pipe WD. In this connection it will be noted that the same water which passes through the water tank T will also pass' through the condenser and function to cool this condenser. To accomplish this the tank outlet is connected by a pipe 40 to the water cooling coils of the condenser WD and from there to the water discharge pipe WD. The control valves for the water line, namely, the valves VR and VD, are associated with this line in the same manner as shown in Figure 1, it being noted that there is a section 17 in which the valve VD is positioned and a section 18 in which the valve V-R is positioned. The valve VR will be connected to be controlled by the high head pressure of the compressor by means of the tube .19. I I

The valve VD, however, which is to regulate the flow of water to the tank during the defrosting cycle, will be controlled by having its tube 39 connected to the conduit 13 between the condenser and the reversing valve, which, during defrosting, will become the suction line for the compressor, due to the functioning of the re versing valve. The pressure in this conduit is accumulated from the evaporation of the refrigerant in the condenser and the pressure which will be supplied from a pressure regulator valve PR, which it will be noted is positioned in a pipe 41 extending between the top of the receiver and the conduit 13. The pressure in conduit 13' during defrosting is thus established by the amountof heat supplied thereto, which in turn will be controlled by the amount of water which is permitted to flow through the regulating valve VD during the defrosting cycle. The regulation of the valve VD will thus not be directly responsive to a function of the heat in the tank T, as was the valve V1) in the system of Figure l, but it will be responsive to an indirect function of the heat of this water in the tank because the heat in Water will control the pressure in the conduit 13 to which the bellows 37 of the valve VD is connected by the small tube .39.

The pressure regulating valve PR may be of any well known construction and the purpose thereof is to relieve the pressure in the receiver when defrosting is initiated. By so relieving the pressure there will then be assured an immediate return of liquid from the evaporator to the receiver. To control the pressure regulating valve there is a small tube 42 connected to a bulb43 which is placed on the conduit 13 between the condenser and the As soon as defrosting is initiated the bulb will begin to have a pressure change and function to cause the pressure relief valve to immediately open so that pressure can be released from the receiver to the suction side of the compressor. In the system disclosed in Figure 4 it will also be noted the line 44 connecting the condenser to the reseiver extends into the bottom of the receiver so that liquid not vaporized from the receiver can be forced directly into the condenser during the defrosting cycle and the condenser can then act as a secondary evaporator or heat exchanger to vaporize the refrigerant because the condenser shown is of the water cooled type and water will be circulated around the coils of the condenser after passing through the tank T surrounding the receiver.

The operation of this refrigeration and defrosting system of Figure 4 is substantially the same as that shown in Figure 1. The valve VR will function during the refrigeration cycle to take care of any abnormal conditions on the system causing excessive head pressures on the compressor. When defrosting is initiated by the operation of the reversing valve RV, the tank T of water surrounding the receiver will act as a heat exchanger to evaporate liquid refrigerant in the receiver as heat will be supplied into the tank by the opening of the valve VD when conditions of the system require such opening. In addition to the tank T acting to evaporate liquid, the condenser DW will also have additional functioning to evaporate refrigerant beside the functioning of the receiver because the water passing through the tank surrounding the receiver also passes through the coils surrounding the condenser before passing to the water discharge pipe/ When defrosting is initiated there is assurance that liquid can quickly flow from the evaporator to the' receiver as the pressure regulating valve PR will open and relieve the pressure in the receiver. With liquidquickly returned from the evaporator to the receiver, the liquid can begin immediately to absorb heat from the Water in the tank and then pass into the condenser where it can absorb additional heat since this condenser will then be acting as a secondary evaporator. The defrosting cycle will then be as rapid as possible.

in Figure 5 there is still another refrigeration system and defrosting system disclosed. This system is also of the type in which the condenser DW is water cooled. All the parts of the refrigeration system which are the same as those shown in Figure 4 are indicated by the samerefer-ence characters. The'system of Figure 5 does not, however, have a water tank surrounding the receiver. In place of such a tank there is provided another tank LT which is inserted in the line L between the evaporator and the receiver. The line L has incorporated therein inside the tank LT a liquid heating coil LH. Water-is supplied to the tank LT through the water line WL and water is discharged from the tank to the condenser through a pipe 45. The water line to the tank LT is controlled by the two valves VD and VR, VD being in the pipe section 17 and the valve VR being in the pipe section 18 in the same manner as in the other refrigeration and defrosting systems already described. In-the refrigeration and defrosting systems of Figure 5, the valve VR will be controlled by being connected by a tube 19 with the conduit 13 in the same manner as before so that this valve VR will be normally closed during refrigeration and will be caused to open under an abnormal head pressure on the compressor. The valve VD, however, which is to control the flow of water to the tank LT and the condenser during defrosting, will be controlled differently by a bulb 46 which will be connected to the bellows of the valve VD by a small tube 47. The bulb 46 will control the valve VD by the heat in the suction conduit from the condenser to the compressor during defrosting. In other words, the valve VD will be controlled by temperature of the suction line which will be a function of the water temperature due to.

compressor.

thewater surrounding the condenser. It will be noted that the refrigeration system in Figure also has the pressure regulating valve PR and its control is accomplished in the same manner as in the refrigeration system in Figure 4. Also in the Figure 5 refrigeration system the condenser will be connected into the bottom of the receiver in the same manner as in Figure 4.

The operation of the system of Figure 5 is believed :to be obvious from what has already been said with respect to the operation of the system of Figure 4 as these two systems operate substantially the same. When the refrigeration cycle is in operation the valve PR will be closed, as will also the valve VD.

When defrosting is initiated by operation of the reverse valve RV, the valve VR will close, if it is open, and the valve VD will be moved to an open position as soon as it is necessary so that water can flow through the tank LT and the condenser. Also, when defrosting is initiated, the pressure regulating valve PR will open and thereby relieve pressure in the receiver so there will be assurance of immediate flow of liquid from the evaporator to the receiver. The heat which will be absorbed by the small tank LT and the coil LH therein will be small in proportion to the heat contained in the water and capable of being absorbed by the condenser. The purpose for this is to heat the liquid coming from the evaporator only a small amount to raise its pressure only so it can expel liquid from the receiver through the pipe 44 into the condenser where more heat will be absorbed to accomplish most of the vaporization as water flows around the coils of the condenser.

From the foregoing description of the various disclosed refrigeration systems embodying my invention, it will be seen that I have devised a defrosting system which is simple and eificient. Heat is supplied to the refrigerant during defrosting by a completely different substance than the refrigerant, which as disclosed is water. This heat carrying water is fully controlled in accordance with the requirements of the refrigerant during defrosting. The problems which have been present in prior reverse cycle defrosting systems are now overcome by my invention. Defrosting can take place in a very short period of time, which, of course, is advantageous as it assures that the product load being refrigerated will not become damaged. In carrying out my invention I have employed an additional heat exchanger means for evaporating a refrigerant for the purpose of assuring that an adequate supply of hot gas will be available for defrosting. In some instances this heat exchanger is provided separately from the regular components of the refrigeration systems and in other instances the condenser can be employed by causing it to function as an eflicient secondary evaporator or heat exchanger means.

It is not intended to limit the use of this invention to defrosting alone, as the principles involved in reverse cycle defrosting can also be applied to reverse cycle heating for other purposes, especially that part of this invention involving the means and method for supplying heat.

I am aware that many modifications can be made in the particular structures which I have shown by way of example as embodying my invention, all without departing from the fundamental principles of the invention, and I therefore desire it to be understood that the scope of my invention is not to be limited except in accordance with the structure called for by the appended claims and equivalents thereof.

What is claimed is:

1. A reverse cycle refrigeration system comprising, a receiver for refrigerant, an evaporator connected to the receiver, a condenser connected to the receiver, a compressor having its high side connected to the condenser and its low side connected to the evaporator during the refrigeration cycle to circulate refrigerant from the compressor to the condenser, to the receiver, to the evaporator and return to. the compressor, valve means for connecting the .low

side of the compressor to the condenser and the high side of the compressor to the evaporator during the heating cycle, said receiver connected to the evaporator through a heat exchanger during the heating cycle, said heat exchanger conducting the refrigerant in indirect heat exchange relationship with a heat bearing substance other than the refrigerant to transmit heat to the refrigerant to pressurize the receiver and drive liquid refrigerant from the receiver to the condenser where it is evaporated, and means responsive to a condition of the gaseous refrigerant generated by the condenser and on the suction side of the compressor for regulating heat transfer in said heat exchanger to regulate the rate at which refrigerant is supplied to the condenser.

2. A reverse cycle refrigeration system comprising, a receiver for refrigerant, an evaporator connected to the receiver, a condenser connected to the receiver, a compressor having its high side connected to the condenser and its low side connected to the evaporator during the refrigeration cycle to circulate refrigerant from the compressor to the condenser, to the receiver, to the evaporator and return to the compressor, valve means for connecting the low side of the compressor to the condenser and the high side :of the compressor to the evaporator during the heating cycle, said receiver connected to the evaporator through a heat exchanger during the heating cycle for supplying heat :to the liquid refrigerant, and means responsive to a condition of the gaseous refrigerant generated by the condenser and on the suction side of the compressor for regulating heat transfer in said heat exchanger .to regulate the rate at which refrigerant is sup plied to the condenser.

3. In a refrigeration system having a compressor with its low side normally connected to a refrigeration evaporator through a suction line and its high side normally connected to the evaporator through a liquid line, means providing for reverse operation of the system to heat the evaporator including reversing valve means for connecting the high side of the compressor to the evaporator and the low side of the compressor to a heat exchanger for supplying heat to the refrigerant during the heating cycle, means connected to the evaporator during the heating cycle for receiving and heating liquid refrigerant from the evaporator and for supplying liquid refrigerant to the heat exchanger to be evaporated, and means responsive to a condition of the gaseous refrigerant generated by said heat exchanger for regulating heat transfer in said heating means to control the rate at which refrigerant is supplied to the heat exchanger.

4. In a refrigeration system having a compressor with its low side normally connected to a refrigeration evaporator through a suction line and its high side normally connected to the evaporator through a liquid line, means providing for reverse operation of the system to heat the evaporator including reversing valve means for connecting the high side of the compressor to the evaporator and the .l-ow side of the compressor to a heat exchanger for supplying :heat to the refrigerant during the heating cycle, means connected to the evaporator during the heating cycle for receiving and heating liquid refrigerant from the evaporator and for supplying liquid refrigerant to the heat exchanger to be evaporated, said heating means conducting refrigerant in indirect heat exchange relationship with a heat bearing substance other than the refrigerant to transmit heat to the refrigerant, and means re- :sponsive to a condition of the gaseous refrigerant generated by said heat exchanger for regulating heat transfer in said heating means to control the rate at which refrigerant is supplied to the heat exchanger.

'5. In a refrigeration system having a compressor with its low sidenormally connected to a refrigeration evaporator through asuction linesand its high side normally connected to the evaporator through a liquid line, means providing for reverse operation of the system to heat the a 13 evaporator including reversing valve means for connecting the high side of the compressor tov the evaporator and the low side of the compressor to a heat exchanger for supplying heat to the refrigerant during the heating cycle, means connected to the evaporator during the heating cycle for receiving and heating liquid refrigerant from the evaporator and for supplying liquid refrigerant to the heat exchanger to be evaporated, said heating means conducting the refrigerant in indirect heat exchange relation with water for supplying heat to the refrigerant, and valve means responsive to a condition of the gaseous refrigerant generated by said heat exchanger for regulating replacement of water in the heating means to thereby regulate heat transfer in said heating means to control the rate at which refrigerant is supplied to the heat exchanger, said last mentioned valve means including a cooperating valve member and seat and a pressure responsive member controlling movement of the valve member, said pressure responsive member moving the valve member toward its seat to reduce flow of water when the control condition of the gaseous refrigerant from the heat exchanger indicates that there is too much liquid refrigerant in the heat exchanger and away from its seat when the control condition indicates there is not enough liquid refrigerant in the heat exchanger.

6. A reverse cycle refrigeration system comprising, a receiver for refrigerant, an evaporator connected to the receiver, a condenser connected to the receiver, a compressor having its high side connected to the condenser and its low side connected to the evaporator during the refrigeration cycle to circulate refrigerant from the compressor to the condenser, to the receiver, to the evaporator and return to the compressor, valve means for connecting the low side of the compressor to the condenser and the high side of the compressor to the evaporator during the heating cycle, said receiver connected to the evaporator through a heat exchanger during the heating cycle, said heat exchanger conducting the refrigerant in indirect heat exchange relationship with a heat bearing substance other than the refrigerant to transmit heat to the refrigerant to pressurize the receiver and drive liquid refrigerant from the receiver to the condenser where it is evaporated, means responsive to a condition of the gaseous refrigerant generated by the condenser and on the suction side of the compressor for regulating heat transfer in said heat exchanger, and condenser, during the heating cycle and separate means responsive to a condition of the gaseous refrigerant on the high side of the compressor during the refrigeration cycle for regulating the heat transfer in said condenser during the refrigeration cycle.

7. A reverse cycle refrigeration system comprising, a receiver for refrigerant, an evaporator connected to the receiver, a condenser connected to the receiver, a compressor having its high side connected to the condenser and its low side connected to the evaporator during the refrigeration cycle to circulate refrigerant from the compressor to the condenser, to the receiver, to the evaporator, and return to the compressor valve means for connecting the low side of the compressor to the condenser and the high side of the compressor to the evaporator during the heating cycle, said condenser conducting a refrigerant in indirect heat exchange relationship with water to transmit heat between the water and refrigerant, valve means responsive to a condition of the gaseous refrigerant gen erated by the condenser and on the suction side of the compressor for regulating the flow of water through the condenser during the heating cycle, and separate valve means responsive to a condtion of the gaseous refrigerant on the high side of the compressor for regulating flow of water through the condenser during refrigeration cycle.

8. Apparatus for use with a reverse cycle refrigeration system which comprises, a receiver for refrigerant, an evaporator connected to the receiver, a condenser connected to the receiver, a compressor having its high side connected to the condenser and its low side connected T4 to the evaporator during'the refrigeration cycle to circulate refrigerant from the compressor to the condenser, to the receiver, to the evaporator, and return to the compressor and valve means for connecting the low side of the compressor to the condenser and the high side of the compressor to the evaporator during the heating cycle comprising, a heat exchanger adapted to be connected in the'lipe between the evaporator and receiver for supplyingheat to the liquid refrigerant at a point between the evaporator and receiver during the heating cycle, said heat exchanging conducting the refrigerant in indirect heat exchange relationship with water to transmit heat to the refrigerant and pressurize the receiver and drive liquid refrigerant from the receiver into the condenser where it is evaporated, and valve means responsive to a condition of the gaseous refrigerant generated by the condenser and on the suction side of the compressor for regulating heat transfer in said heat exchanger to regulate the rate at which refrigerant is supplied to the condenser.

9. A reverse cycle refrigeration system comprising, a receiver for refrigerant, an evaporator connected to the receiver, a compessor having its high side connected to the receiver and its low side connected to the evaporator during the refrigeration cycle to circulate refrigerant from the compressor to the receiver, to the evaporator and return to the compressor, valve means for connecting the low side of the compressor to the receiver through a first heat exchanger and the high side of the compressor to the evaporator during the heating cycle, said receiver connected to the evaporator through a second heat exchanger during the heating cycle for supplying heat to the liquid refrigerant returning from the evaporator, means responsive to a condition of the gaseous refrigerant generated by the first heat exchanger and on the suction side of the compressor during the heating cycle for regulating heat transfer in said second heat exchanger to regulate the rate at which refrigerant is supplied to the first heat exchanger and means for relieving excess pressure from the receiver at the commencement of the heat ing cycle and conducting such relief pressure to a portion of the system under a lower pressure.

10. In a refrigeration system having a compressor with its low side normally connected to a refrigeration evaporator through a suction line and its high side normally connected to the evaporator through a liquid line, means providing for reverse operation of the system to heat the evaporator including reversing valve means for connecting the high side of the compressor to the evaporator and the low side of the compressor to a heat exchanger for supplying heat to the refrigerant during the heating cycle, said heat exchanger conducting the refrigerant in indirect heat exchange relation with water for supplying heat to the refrigerant, and valve means responsive to a condition of the gaseous refrigerant generated by said heat exchanger for regulating replacement of water in the heat exchanger to thereby regulate heat transfer in said heat exchanger, said last mentioned valve means including a cooperating valve member and seat and a pressure responsive member controlling movement of the valve member, said pressure responsive member moving the valve member toward its seat with an increase in refrigerant pressure and away from its seat with a decrease in refrigerant pressure.

11. The system of claim 8 wherein the last mentioned valve means comprises a valve body having a passageway therethrough, a seat and valve member cooperative therewith controlling flow through the passageway, said valve member urged towards its seat by a pressure responsive member exposed to pressure conditions in the condenser, and resilient means urging the valve away from its seat with a force which is so related to the force of the pressure conditions in the condenser during the heating cycle that the valve member will function to regulate flow through the passageway responsive to such pressure conditions, said force being substantially less References Cited in the file of this patent UNITED STATES PATENTS Singer Apr. '8, 1902 Sayer July 27, 1915 1'55 Candor Ian. 26, 1943 Cocanour Nov. 2, 1943 T1111 et al. Dec. 16, 1947 Sporn et a1. July 4, 1950 Pabst Oct. 10, 1950 Nussbaum Aug. 14, 1951 Schordine Apr. 21, 1953 Malkotf May 12, 1953 La Porte July 14, 1953 

